Malocclusion can negatively affect the self-image, function and quality of life of individuals of all ages. In addition, correction of malocclusions often requires expensive, time-consuming treatment. While many malocclusions are inherited traits or have unknown etiologies, a number of studies during the past 30 years have suggested that non- nutritive sucking habits, such as pacifier use and digit sucking in infancy and early childhood, may cause some malocclusions. More recent studies have indicated that breast-feeding in infancy may help to prevent such problems. However, nearly all of these studies have used limited retrospective designs, and very few have longitudinally assessed these developmental consequences of behavior as they relate to the mixed or permanent dentition. The proposed project will assess the impact of longitudinally-gathered non-nutritive sucking and infant feeding pattern data on the development of dental arch characteristics in deciduous dentition, as a prelude to study of the mixed dentition. It will utilize a defined birth cohort of over 450 children who will be between 4 3/4 and 5 1/2 years during the examination phase of the study period. These children were recruited for The Iowa Fluoride Study, a prospective study of fluoride exposures and dental fluorosis. Parents have already reported on children's feeding habits and non-nutritive sucking behaviors at 3-4 month intervals since birth. The proposed study will collect dental arch and occlusion variables through study models when these children reach about 5 years of age. The study will use both dichotomous and interval-level data collected prospectively on sucking behaviors of children in the cohort, and will use multivariate statistical techniques such as logistic and linear regression to identify variable predictive of certain malocclusions. This study design will a allow a more comprehensive and reliable assessment of the relationships between patterns of nutritive and non-nutritive sucking habits and occlusal or dental arch characteristics than has been reported in other studies. This preliminary study will allow investigators to determine the feasibility of using this previously-collected data in a later study of the mixed dentition in this cohort. This study and the potential future study provide the information necessary to make informed, scientifically-based assessments of the risks for developing malocclusions and recommendations on management of sucking habits.